Driving practices make more difference than any minor changes you can make. Anticipate lights. Brake lightly, accelerate lightly. Moderate speed. Keep the windows and sunroof closed. Use the vacuum gauge that masquerades as a fuel consumption gauge to help keep a light foot on the throttle.

And if you want to really improve your mileage, drive a vehicle that weighs a couple of thousand pounds less.

X5 ///M CSL, hehe (SAVSL?)

Avoid traffic. Get navigation that goes around it.

i pretty much gave on the fuel efficiency when i got the 4.6 - it is like a drug, when you press the gas pedal, and the elephant sized beast sprints up like a cheetah... but the, again, watching the fuel gauge moving like it was a second hand on a watch - not much fun... I averaged 13 MPG in 4.6...

in 4.8 my average now (precisely calculated by excel spreadsheet, as i started to keep fuel receipts and write mileage) is 16.08113, which is $0.22 a mile at current prices...

Gallons Total $ Miles driven MPG $ per mile
261.3 $937.29 4202 miles 16.08113 $0.22

buy a motorcycle ...or buy some light weigh wheels ..people don't think about it much my stock rims that came with a BMW weigh only 10lbs lighter then my 22inch with low profile tires...usually low profile tires are heavier then regular that said ..dang BMW couldn't think of making wheels little bit lighter. Toyota suv makes light wheels i changed my friends brakes and wanted to see the difference it was huge...bottom line lighter wheels would help
And buy the way tornado fuel saver and other gizmos don't.

Eat more fruits and vegetables. Lose the rear seats,drive like a grammars ,etc...

Lol are you referring to the myth busters where they put golf ball dimples on a ford Taurus?

I've found that I can get better MPG at 75 mph behind a few semis then at 70 mph without drafting. I follow about 1 sec behind.

The biggest mileage killer is brake application.

-Get a haircut every week
-take a dump before each trip.
-Give the car a wash to remove all the heavy dirt
also don't forget to vacuum your carpets.
-Drive on E as much as possible.
-Use cruise control on stop and go traffic
-If you car pool then don't do it anymore. Make
them take public transportation.
-use 0w10 oil